By electronic tag is meant an assembly comprising a substrate, a near-field communication circuit comprising an electronic chip and a near-field communication antenna, allowing contactless communication to be established with an external device for exchanging data. The antenna is generally connected to the electronic chip and serves not only as a means of contactless communication but also to produce the energy needed to feed the electronic chip.
In order to ensure optimal transmission of the data between the tag and the external device regardless of the metallic environment of the tag, the tag is provided with a magnetic shielding layer capable of protecting the near-field communication circuit.
This is particularly advantageous, particularly for a “contactless payment” application embedded in a mobile telephone, the mobile telephone including a battery and sometimes even a metal case which can greatly harm the quality of data transmission to an outside reader when the tag is affixed to the telephone.
A contactless tag designed for application in a metallic environment is already known in the state of the art, particularly from document WO2008/065278. In this document, the tag includes an intermediate layer made of a magnetically hyperconducting material, placed against a substrate bearing the antenna and the microcircuit. The assembly made up of the substrate, the antenna and the microcircuit is subsequently embedded in a cover made of plastic by lamination or casting.
The disadvantage of the tag thus obtained is that it remains relatively thick due to the presence, in addition to the substrate bearing the antenna and the microcircuit, of the intermediate layer and the cover. In addition, in this document, the dimensions of the tag are defined by the dimensions of the antenna which extends over a relatively large surface area.
There is at present a need for a customizable tag, of small thickness, of small dimensions and low manufacturing cost. In addition, this tag must be designed to operate in a metallic environment such as for example the vicinity of a mobile telephone.